function [b,a]=bpfilter(freq)

center = freq/4000;
F = [center-73/4000 center center center+73/4000];
A = [0 1 0];
% 10^(0.2/20)/10^(60/20) = 0.001
DEV = [0.001 1 0.001];
[N,Wn,BTA,FILTYPE] = kaiserord(F,A,DEV);
b = fir1(N, Wn, FILTYPE, kaiser( N+1,BTA ),'noscale');
a = [1];
